This invention relates to the preparation of acetal derivatives of polyunsaturated fatty esters. The invention further relates to the compositions thus prepared and to their use as primary plasticizers for poly(vinyl chloride).
A plasticizer is a material which is incorporated in a plastic and which functions to increase its workability and flexibility. The search for acceptable plasticizers has been a very active one. In 1934 about 56 plasticizers were being produced and from that time until about 1934, over 20,000 plasticizer compositions had been disclosed in the literature, 60 of which are among the 500 presently available (cf. Encyclopedia of Polymer Science and Technology, Vol. 10, John Wiley and Sons, Inc., 1969, p. 230).
The types of organic plasticizers in general use are liquids having moderately high molecular weights and include esters of carboxy acids, esters of phorphoric acids, hydrocarbons, halogenated hydrocarbons, ethers, polyglycols, and sulfonilamides.
Dioctyl phthalate (DOP) is the most widely used primary plasticizers for poly(vinyl chloride), PVC, and accounts for about 25 percent of the total market (Encyclopedia of Polymer Science and Technology, supra, p. 231). For reasons of compatibility, costs, process behavior, and performance, primary PVC plasticizers are limited to various dibasic acids and phosphate esters, epoxidized oils and resins, glycolates, mellitates, and polyesters of various dibasic acids with glyclols, pentaerythritol derivatives, and sulfonates. Secondary PVC plasticizers are generally limited to various aromatic and mixed aromatic aliphatic oils, chlorinated paraffins, polyalpha methyl styrene derivatives and esters of high molecular weight alcohols, and organic acid (cf. Modern Plastics Encyclopedia, Vol. 50, No. 1A, 1973-74, pp. 254-266).
The object of this invention is the provision of compositions which are useful as primary plasticizers for PVC, which are easily prepared from inexpensive starting materials such as vegetable oils, and which impart to the PVC physical properties equal or superior to those of PVC compositions plasticized with commercially available plasticizers such as DOP.
In accordance with the above object, we have found a method of preparing primary plasticizers for PVC comprising the following steps:
a. reacting methyl diformylstearate, or methyl triformylstearate, or mixtures of the same with trimethyl orthoformate and methanol, or with ethylene glycol to form the corresponding dimethyl acetal or ethylene acetal derivatives of the methyl diformylstearate, or of the methyl triformylstearate, or of the mixtures; and PA0 B. recovering the resulting poly(dimethyl acetal) or poly(ethylene acetal) fatty methyl esters from the reaction mixture of step (a).
The compositions thus prepared are then fused in plasticizer amounts with PVC.